ide: add ide_use_fast_pio() helper (v3)

* add ide_use_fast_pio() helper for use by host drivers

* add DMA capability and hwif->autodma checks to ide_use_dma()

  - au1xxx-ide/it8213/it821x drivers didn't check for (id->capability & 1)

    [ for the IT8211/2 in SMART mode this check shouldn't be made but since
      in it821x_fixups() we set DMA bit explicitly:

               if(strstr(id->model, "Integrated Technology Express")) {
                       /* In raid mode the ident block is slightly buggy
                          We need to set the bits so that the IDE layer knows
                          LBA28. LBA48 and DMA ar valid */
                       id->capability |= 3;            /* LBA28, DMA */

       we are better off using generic helper if we can ]

  - ide-cris driver didn't set ->autodma

    [ before the patch hwif->autodma was only checked in the chipset specific
      hwif->ide_dma_check implementations, for ide-cris it is cris_dma_check()
      function so there no behavior change here ]

v2:
* updated patch description (thanks to Alan Cox for the feedback)

v3:
* updated for scc_pata driver

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/ide/ide-lib.c b/drivers/ide/ide-lib.c
index bea5e13ee36..8afce4ceea3 100644
--- a/drivers/ide/ide-lib.c
+++ b/drivers/ide/ide-lib.c
@@ -205,6 +205,21 @@ int ide_dma_enable (ide_drive_t *drive)
 
 EXPORT_SYMBOL(ide_dma_enable);
 
+int ide_use_fast_pio(ide_drive_t *drive)
+{
+	struct hd_driveid *id = drive->id;
+
+	if ((id->capability & 1) && drive->autodma)
+		return 1;
+
+	if ((id->capability & 8) || (id->field_valid & 2))
+		return 1;
+
+	return 0;
+}
+
+EXPORT_SYMBOL_GPL(ide_use_fast_pio);
+
 /*
  * Standard (generic) timings for PIO modes, from ATA2 specification.
  * These timings are for access to the IDE data port register *only*.